1. The Field of the Invention
The present invention is directed toward a method and apparatus for applying heat to a transdermal drug delivery system. More specifically, the invention is a securable compartment with a corresponding freely transferrable heating element for use with dermal drug delivery patches.
2. The Background Art
It has been discovered recently that the transdermal delivery of certain drugs can be facilitated by the application of heat. Controlled heat is provided to transdermal drug delivery patches using various techniques and apparatus such as heat generating patches. The heat generating patches sometimes utilize heat generated from chemical reactions, such as an oxidation reaction, or may utilize heat generated by an electrical current or some other method. One of the disadvantages of prior art heating apparatus for the transdermal drug patches is that the heating element must be secured to the transdermal patch without compromising the transdermal drug patch's attachment to the user's skin. In other words, sometimes when a user attempts to attach, replace, or adjust a heating patch or similar device, the drug delivery patch can become dislodged or otherwise made less secure. If the drug patch is not properly situated, the drug delivery system may be compromised. It is important in transdermal drug delivery that the skin be in contact with the formulation of the drug delivery patch to achieve efficient drug transfer.
Several methods for attaching or integrating a controlled heating element have been taught in the prior art. For example, wraps, adhesives, and tapes have all been suggested as potential ways for attaching a heating element to a patient's body or to a transdermal drug patch. Attempting to attach a heating element to a transdermal drug patch these ways has several disadvantages.
When a prior art adhesive technique is used to apply the heating element to the drug patch, the process of applying the heating element to the patch may cause the drug delivery patch to become less secure. To apply the heating element using adhesive, the areas of the heating element that contain the adhesive must be pressed firmly against the heating patch to secure the heating element to the patch. During this process, the drug delivery system may be unintentionally compromised.
In the event that the user needs to remove, replace or change the heating element, any attempts to remove the heating element may cause the adhesive of the transdermal patch to be compromised, and thus to compromise the drug delivery. The continued removal and replacement of the heating element may cause the transdermal drug patch to lose enough adhesive that the drug patch does not properly contact the skin and thereby become less effective and less secure.
A significant problem with using prior art wraps to secure a heating element to a transdermal drug patch is the potential for the heating element and/or the drug patch to become dislodged. If the heating element is secured using a wrap or tie, as the heating element is being tied to or wrapped into the user or the drug patch on the user, the process of tying or wrapping the heating element can cause the drug patch to lose contact with the skin of the patient and thereby compromise the drug delivery.
Another disadvantage of prior art teachings is the inconvenience associated with trying to remove a heating element that is attached by a wrap. In order to change or remove the heating element, the user must attempt to unwrap the heating element from the transdermal patch without disturbing the transdermal patch. This can be particularly difficult if the user needs to make the change quickly or if the patch is located in a position that makes delicately removing and replacing the heating element wrap impractical. For example, if the heating element were secured to a patch by a wrap that went around a patient's torso, frequent removal of the wrap could require substantial extra effort and work on the part of the patient and/or the user.
Another disadvantage of prior art teachings is the cost of integrating a heat element with a transdermal patch, particularly for heating elements that have limited uses and applications. If a patient requires a certain level of heating in one circumstance and a different level of heating in another, then the integrated patch must be removed and an entirely different patch with an appropriate heating level must be applied. Alternatives to this would require complex patch designs that attempt to control or modify the amount of heat generated by the heating element. Thus, using an integrated patch may increase manufacturing costs significantly. Moreover, modified and integrated designs may prove to be less reliable and may be prone to misuse.
Another disadvantage of the prior art is the potential for abuse where the heating element neither corresponds to a specific patch nor is integrated with a particular patch. If a heating patch can be freely used with any given transdermal device, there is a potential for the patch to be abused by a patient or misused by the user. For example, the patient may apply a heating element that induces an absorption rate that is too fast or delivers too much drug. Conversely, the user may apply a heating element that fails to supply sufficient heat for a particular treatment. Thus, where the patches do not correspond to the heating elements used with them, there is a potential for abuse or misuse.